package demo;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * 这个类用来
 */

public class UserMapper {
    public int insert(User user){
        try(Connection conn = DBUtil.getConnection();) {
            String sql = "INSERT INTO user(username,password,nickname,age) "+
                          "VALUES(?,?,?,?)";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1,user.getUsername());
            ps.setString(2,user.getPassword());
            ps.setString(3,user.getNickname());
            ps.setInt(4,user.getAge());
            return  ps.executeUpdate();
        }catch (SQLException e){
            e.printStackTrace();
        }
        return 0;
    }

    public User selectByUsername(String username){
        try(Connection connection = DBUtil.getConnection();) {
            String sql = "SELECT id,username,password,nickname,age "+
                    "FROM user "+
                    "WHERE username=? ";
            PreparedStatement ps = connection.prepareStatement(sql);
            ps.setString(1,username);
            ResultSet rs = ps.executeQuery();
            if (rs.next()){
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("username"));
                user.setPassword(rs.getString("password"));
                user.setNickname(rs.getString("nickname"));
                user.setAge(rs.getInt("age"));
                return user;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 修改用户信息
     * 根据传入的user对象中的用户名，修改用户的密码，昵称，年龄三个信息
     * @param user
     * @return
     */
    public int update(User user){
        try (Connection connection = DBUtil.getConnection();){
            String sql = "UPDATE user " +
                    "SET password=?,nickname=?,age=? " +
                    "WHERE username=?";
            PreparedStatement ps = connection.prepareStatement(sql);
            ps.setString(1, user.getPassword());
            ps.setString(2, user.getNickname());
            ps.setInt(3, user.getAge());
            ps.setString(4, user.getUsername());
            return ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return 0;
    }

    /**
     * 查询所有用户信息
     * 在User表中每一条记录都可以使用一个User对象表示
     * @return
     */
    public List<User> selectAll(){
        List<User> users = new ArrayList<>();
        try(Connection connection = DBUtil.getConnection()) {
            String sql = "SELECT id,username,password,nickname,age "+
                    "FROM user";
            Statement statement = connection.createStatement();
            ResultSet rs = statement.executeQuery(sql);
            while (rs.next()){
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("username"));
                user.setPassword(rs.getString("password"));
                user.setNickname(rs.getString("nickname"));
                user.setAge(rs.getInt("age"));
                users.add(user);
            }
            return users;
        }catch (SQLException e){
            e.printStackTrace();
        }
        return null;
    }

}
